Table 1 Some chemical inhibitors of auxin biosynthesis

BBo

3-chlorophenylboronic acid, 4-biphenylboronic acid

YUCCA

Competitive inhibitor

[50]

PPBo

4-phenoxyphenyl-boronic acid

YUCCA

Competitive inhibitor

[50]

Ponalrestat

2-(3-(4-Bromo-2-fluorobenzyl)-4-oxo-3,4-dihydrophthalazin-1-yl)acetic acid

YUCCA

Substrate antagonist

[51]

Yucasin

5-(4-chlorophenyl)-4H-1,2,4-triazole-3-thione

YUCCA

Competitive inhibitor

[52]

Yucasin DF (YDF)

5-[2,6-difluorophenyl]-2,4-dihydro-[1,2,4]triazole-3-thione

YUCCA

Competitive inhibitor

[53]

Pyruvamines (PVM) “Type I compounds”

PVM1169; L-alpha-(aminooxy)-3-(naphthalen-2-yl)propanoic acid

TAA1

Competitive inhibitor

[20]

Pyruvamines (PVM) “Type II compounds” (Derivatives of Type I compounds)

PVM2153; Benzene propanoic acid, 3,4-dichloro-α-[(1,3-dihydro-1,3-dioxo- 2H-isoindol-2-yl)oxy]-, methyl ester

TAA1

Competitive inhibitor

[20]

L-Kynurenine (Kyn)

(2S)-2-Amino-4-(2-aminophenyl)-4-oxobutanoic acid

TAA1

Alternative substrate/ Competitive inhibitor

[54]

AVG

Aminoethoxyvinyl-glycine

TAA1

Slow-binding inhibition

[55]

AOPP

L-aminooxyphenyl-propionic acid

TAA1

Competitive inhibitor

[55]

AOA

Amino-oxyacetic acid

TAA1

[55]

AOIBA

2-amino-oxyisobutyric acid

TAA1

[55]

Indoleacrylic acid

trans-indole-3-acrylic acid

Trp synthase β and α

Allosteric inhibitor

[56, 57]

(1-Fluorovinyl)glycine

α-(1′-fluoro)vinyl glycine

Trp synthase β

PLP-enzyme mechanism-based inhibitor

[58]

Arylsulfide phosphonates

[4-[(2-aminophenyl) sulfanyl]butyl] phosphonic acid

Trp synthase α

Transition state analog

[59, 60]

Indoline-5-sulfonamides

1-(2-Fluorobenzoyl)-N-methyl-5-indoline sulfonamide N-Methyl-1-[(5-methyl-2-thienyl)carbonyl]-5-indolinesulfonamide

Trp synthase inter- subunit interface

Allosteric inhibitor

[61]

Sulfolane and indole-5-sulfonamide

GSK1, (3R,4R)-4-[4-(2-chlorophenyl)piperazin-1-yl]-1,1-dioxothiolan- 3-ol); GSK2, (1-[2-fluorobenzoyl]-N-methyl-2,-

3-dihydro-1H-indole-5-sulfonamide)

Trp synthase inter- subunit interface

Allosteric inhibitor

[62]

Aryl sulfonamides

[F9]; N-(4’-Trifluoromethoxy benzenesulfonyl)-2-aminoethyl Phosphate

Trp synthase β

α-Site allosteric ligand

[63]

Benzamide

N-(4-Carbamoyl benzyl)-5-(3-chloro phenyl)-1,2-oxazole-3-carboxamide

Trp synthase α

α-Site ligand

[64]